Treatment of produced water from a subterranean formation

ABSTRACT

Systems for water treatment may include a drying tunnel, wherein the drying tunnel may comprise: a blower, wherein the blower may be fluidly coupled to an end of the drying tunnel; nozzles disposed between the distal end of the drying tunnel and the blower; and a chamber configured to collect solids; wherein the drying tunnel may be configured to evaporate water.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-provisional applicationSer. No. 15/394,623 filed Dec. 29, 2016, issuing as U.S. Pat. No.10,494,269 on Dec. 3, 2019; which is hereby specifically and entirelyincorporated by reference.

BACKGROUND

Within recent years, the oil and gas industry has developed the use ofhydraulic fracturing to produce what was once considered nonproductiveoil and gas formations. This hydraulic fracturing technology may requirethe use of high volumes of water to be pumped into subterranean wellsunder tremendous rates and pressures to pry rock apart, thereby allowingthe oil and gas that is trapped within the matrix of the oil and gasformations to migrate to the wellbore and production casing. Althoughthe use of this technology may have allowed high volumes of oil and gasrecovery from the oil and gas formations, the use of these large volumesof water has been widely scrutinized. Because the water that may be usedduring these fracturing operations is preferably clean and free fromcontaminants, current technologies may use fresh water sources that maynormally be used for irrigation and human consumption. The use of thesefresh water supplies may have an impact on the availability of freshwater for human consumption and irrigation.

Although the water that may be pumped into the oil and gas formationsmay be recovered over the production life of the oil and gas well, thewater may become contaminated with chemicals from the fracturing processand minerals that are leached from the producing reservoir during theproduction of the well. Many oil and gas reservoirs may have beencreated from decomposed organic matter generated from oceanic sea beds.Fresh water may mix with the salt water that may typically be producedfrom the hydrocarbon formations making both the frac water and theformation water unsuitable for human consumption or reuse for hydraulicfracturing. This water that may be produced or that flows back from thewell may then be disposed of by pumping it into deep nonproductive oiland gas formations. This cycle may be repeated for each well and may usehundreds of thousands of barrels for each operation.

Recently this disposal process has come under scrutiny due to increasedseismic activity that has occurred in conjunction with the pumping ofthe water into these subterranean reservoirs. It is for this reason thatthe industry has an increased need to find a way to reduce the amount ofwater that may be disposed of in these underground formations. Thevolume of water and the high level of the Total Dissolved Solids (“TDS”)may make it difficult to filter using a Reverse Osmosis unit for surfacedischarge purposes. In the past, distillation systems may have been usedto evaporate and condense the water for discharge purposes. However, thecost for the energy or BTUs to distill the water proved to often beuneconomical to use on a large scale basis.

In another instance, evaporation processes may have been used toeliminate the water and recover the solids contained in the water. Thesesystems may spray large volumes of water into the air using blowers andmisting systems to evaporate the water. The solids may then fall intocollection or evaporation pits. This process may be problematic due towind causing the solids or salt to be blown outside of the evaporationpits or collection areas. This may then be compensated by the use ofwind walls to prevent the drifting of the sprayed/misted water. Thesewind walls may generate static areas of high humidity air masses,thereby reducing the efficiencies of the evaporation process. In thepast, this may have been compensated for by setting up wind sensors thatwould turn blowers on and off on different sides of the evaporation pitsto compensate for wind direction.

In another instance, an enclosure may be placed over the entireevaporation pit to prevent drift caused by the wind. In this case, theenclosure may be ventilated to continuously move air into and out of theenclosure to avoid saturation of the air mass.

Therefore, there may exist a need for a system to evaporate and/orreduce the volumes of water that are being disposed of without theissues of containment that are generated by blowing high solids waterinto the atmosphere, and allowing them to fall into collection orevaporation pits.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of some of the embodiments ofthe present disclosure and should not be used to limit or define thedisclosure.

FIG. 1 illustrates a chart showing volumetric air requirements forevaporation based on the temperature of the air mass.

FIG. 2 illustrates a drying tunnel in accordance with embodiments of thepresent disclosure.

FIG. 3 illustrates a drying tunnel positioned on a vehicle trailer inaccordance with embodiments of the present disclosure.

FIG. 4 illustrates a plurality of drying tunnels positioned on vehicletrailers in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

Water may exist naturally in subterranean formations and may be producedin conjunction with hydrocarbons from the subterranean formations. Watermay also be injected into a subterranean formation to stimulatehydrocarbon production (e.g., hydraulic fracturing or fracking). Whenthe water is produced from the subterranean formations, it may compriseamounts of dissolved salts and other substances, which may make itunsuitable for agriculture and human consumption.

The present disclosure may generally relate to the treatment ofcontaminated water (e.g. salt water/brine), and more specifically to theevaporation of water produced from a subterranean formation. Embodimentsof the present disclosure may include mechanical agitation withsubmerged aeration to saturate an air mass, thereby accelerating theevaporation process, without generating the environmental concerns ofhigh TDS fluids being carried outside of the evaporation zone. Brine maycomprise a brine solution comprising at least 10 wt % NaCl. In someembodiments, brine may comprise a brine solution comprising about 10 wt% NaCl to about 25 wt % NaCl. In other embodiments, brine may comprise abrine solution comprising more than 25 wt % NaCl. Other ranges mayinclude ranges above what may be considered dischargeable to surfaceground waters. As the water becomes concentrated and saturated withsalts, the heavier water may be pulled off and then injected intosubterranean disposal wells at significantly lower volumes then normal,thereby reducing the subsurface pressurization and aiding in preventionof seismic occurrences.

By allowing air to be mixed and released below the water surface, theair mass may become saturated before it breaks the surface of the water.Systems, methods and devices of the present disclosure may substantiallyimprove the evaporation efficiency of the water by allowing the air masstemperature to rise to the temperature of the water contained in a pitthat the air mass is in contact with, which may be above the temperatureof the air mass above the pit. This may be important during wintermonths where the air mass temperatures within certain regions may bebelow 30° F. Systems, methods and devices of the present disclosure mayalso allow for high rates of oxygen transfer due to the high volumes ofair (e.g., 100,000 cubic feet of air per minute) that may be moved. Byincreasing the air that may be in contact with the water, the amount ofdissolved oxygen may be increased. Standard aeration systems may use asmuch as 1,500 horsepower to move 5,000 cubic feet of air per minute. Ofthis 5,000 cfm, only a small percentage of the air mass may go intosolution in the form of dissolved oxygen. This may typically be around2% of the oxygen that is within the air mass, which may render thesystem 98% inefficient. To overcome these inefficiencies, higher volumesof air may be moved at lower horsepower (“HP”). In comparison, a 50 HPaxial fan may move 100,000 cubic feet per minute (“cfm”), therebyincreasing the amount of dissolved oxygen per horsepower by more than 30times. In the past, aeration systems have relied on moving air (e.g., anair mass) into water in order to infuse oxygen into the water or settingup blowers that would feed headers, and the headers would then feedcontrol lines that went into the water at various depths to feeddiffusers or other mechanisms to distribute the air into the water.Systems, methods and devices of the present disclosure may eliminate theneed for headers or control lines to distribute the air into the water.

In certain embodiments, flow back and/or produced water may be pumped orhauled into a storage pit or storage reservoir via trucks or othergathering systems. Blowers may be placed into the pit and spaced basedon volumetric requirements for evaporation or for aeration purposes.

FIG. 1 illustrates a chart showing volumetric air requirements forevaporation based on the temperature of the air mass. It should be notedthat the number of pounds of water that may be evaporated per 1,000cubic feet of air may be highly dependent on the initial relativehumidity of the air mass and the temperature of the air. This relativehumidity may fluctuate during the course of the day. Therefore, systems,methods and devices of the present disclosure may include programsconfigured to turn on systems and devices of the present disclosureduring low relative humidity times of about 30% to about 70%, therebylowering the cost of energy and improving the efficiencies of a vaportransfer. For example, if the number of pounds of water per 1,000 cubicfeet of air is 1, and the relative humidity is 70%, then the pounds ofwater that the 1,000 cubic feet may be capable of absorbing beforebecoming saturated or reaching 100% relative humidity may be 0.30 or 30%of the 1 pound per thousand cubic feet. Therefore, a blower that maymove 10,000 cubic feet per minute may be capable of evaporating about 3pounds of water per minute at an initial air mass relative humidity of70%. However, at an initial relative humidity of 30%, about 7 pounds ofwater per minute may be evaporated. Based on this calculation, theaverage annual relative humidity may be used to calculate the number ofevaporation devices and the size of the evaporation devices to achieve acertain volume of evaporation per day. The moisture holding capacity ofair may be 1 lb of water per 1,000 cubic feet of dry air. The moistureholding capacity of air at 100° F. may be about 10 times the moistureholding capacity of air at 30° F. This may be an important observation,especially when working in areas where air temperatures may be lowduring certain times of the year.

As shown in FIG. 2, in some embodiments, water from storage pit 102,which may include brine, may be pumped to a drying tunnel or evaporatorand collection tunnel where additional air may be pumped into theevaporation tunnel while the water is sprayed into the air mass withinthe drying tunnel. Brine may comprise a brine solution comprising atleast 10 wt % NaCl. In some embodiments, brine may comprise a brinesolution comprising about 10 wt % NaCl to about 25 wt % NaCl. In otherembodiments, brine may comprise a brine solution comprising more than 25wt % NaCl. Other ranges may include ranges above what may be considereddischargeable to surface ground waters. As the water becomesconcentrated and saturated with salts, the heavier water may be pulledoff and then injected into subterranean disposal wells at significantlylower volumes then normal, thereby reducing the subsurfacepressurization and aiding in prevention of seismic occurrences.

FIG. 2 illustrates tunnel 130 (e.g., a drying tunnel). Tunnel 130 may bea hollow conduit or recess. Tunnel 130 may be utilized in combinationwith evaporation unit(s) disclosed in co-pending U.S. patent applicationSer. Nos. 15/394,612 and 15/394,627 or tunnel 130 may be utilized byitself. Tunnel 130 may include proximal end 132 and distal end 134.Distal end 134 may be open to the atmosphere. Tunnel 130 may include ashape of a drum or barrel. Tunnel 130 may comprise blower 136, nozzles138, heaters 140 and a chamber 142 (e.g., a solids collection chamber).Tunnel 130 may be positioned at an inclination angle, a, from about 1°to about 90° relative to horizontal (e.g., x axis, as shown).Alternatively, inclination angle, a, may be about 30° to about 90°, orabout 40° to about 50° (e.g., 45°). Tunnel 130 may be of a sufficientsize and inner diameter and may be heated to prevent any carry over ofthe air mass. Tunnel 130 may include an inner diameter of about 8 feetto about 12 feet and a length of about 50 feet to about 200 feet. Tunnel130 may be made of any suitable material, such as, for example, metal(e.g., steel, alloys).

Blower 136 may be fluidly coupled to proximal end 132 by any suitablemeans, such as, welds. Blower 136 may include a high volume blower andmay move over 100,000 cubic feet of air per minute. In certainembodiments, blower 136 may move about 10,000 cubic feet of air perminute to about 500,000 cubic feet of air per minute. The inner diameterof blower 136 may be about 12 inches to about 96 inches. Blower 136 maybe electrically powered and may include a motor rated from about 7horsepower to about 150 horsepower. Blower 136 may also be powered byany other suitable means. Blower 136 may include ducted fans. Blower 136may be placed at the lower end of tunnel 130 (e.g., proximal end 132)with a collection point (e.g., chamber 142) for the solids above theblower 136. Blower 136 may move over 100,000 cubic feet of air perminute. In certain embodiments, blower 136 may move about 10,000 cubicfeet of air per minute to about 100,000 cubic feet of air per minute.Blower 136 may aid in evaporating the water within tunnel 130. Blower136 may be electrically powered and may include a motor rated from about7 horsepower to about 150 horsepower. Blower 136 may have an innerdiameter from about 8 feet to about 12 feet.

Nozzles 138 may be disposed between the blower 136 and heaters 140.Nozzles 138 may be nozzles used in misting and evaporation systems. Insome embodiments, nozzles 138 may include a plurality of 32 nozzles thatmay spray about 30 gallons per minute into the tunnel 130 with an airtemperature of about 100° F. and an air rate of about 100,000 cfm. Basedon the evaporation chart, the air mass at that temperature may becapable of holding about 300 lbs of water per min, or absorbing about 30gallons per minute of water. The rate of water exiting the nozzles 138may be adjusted to compensate for the influent air temperature to reachfull evaporation. Nozzles 138 may be fluidly coupled to storage pit 102(e.g., via line 152 and pump 154). Storage pit 102 may supply nozzles138 with water. Nozzles 138 may be configured to spray water (e.g.,water from storage pit 102) into tunnel 130.

Heaters 140 (e.g., electrically powered heaters) may include bandheaters and/or direct contact heaters. Any other suitable heaters may beutilized. Heaters 140 may be incorporated on the outside surface 144 oftunnel 130 to heat the air mass and improve the vaporization exchangeinto the air mass. The heating temperatures may range from about 70° F.on cold days to over about 130° F. on hot summer days. Heaters 140 mayaid in evaporating the water within tunnel 130.

Chamber 142 may be disposed between blower 136 and nozzles 138. Chamber142 may be configured to receive/collect solids falling out of (e.g.,separating from) the water as the water evaporates within tunnel 130.Chamber 142 may include an auger 146 for removing solids from chamber142. Chamber 142 may have a diameter from about 8 inches to about 10inches or more. Auger 146 may be of about the same diameter of chamber142.

In certain embodiments, tunnel 130 may be positioned on a trailer (e.g.,vehicle trailer). FIG. 3 illustrates tunnel 130 positioned on trailer148. Tunnel 130 may be coupled to trailer 148 via lifters 150 (e.g.,hydraulic lifters—lifters actuated via fluid). Lifters 150 may lowerand/or raise tunnel 130, thereby adjusting an inclination angle (e.g.,n) relative to horizontal (e.g., x axis, as shown). Although FIG. 3illustrates a single tunnel 130 and trailer 148, it should be noted thata plurality of tunnels 130 and trailers 148 may be utilized, asillustrated on FIG. 4.

During operation of tunnel 130, water from storage pit 102 may be pumpedto nozzles 138. Nozzles 138 may spray water from storage pit 102 intothe interior of tunnel 130. The nozzles 138 may spray at a rate belowthe absorption rate of the air mass. Blower 136 may capture air from thesurrounding area and blow/force the air through tunnel 130 and outdistal end 134 as heaters 140 heat the air and water mixture. As thewater evaporates, the solids in the water (e.g., salt) may fall out ofthe water and gravitationally move to the bottom of the angled tunnel130 where they are collected in chamber 142. The solids in chamber 142may be augured and transported for recycling or disposal. Tunnel 130 maybe scraped to prevent buildup of salts inside of the inner surface oftunnel 130. The scraping may be accomplished by any suitable means.

In certain embodiments, a drying tunnel may comprise a blower, whereinthe blower may be fluidly coupled to an end of the drying tunnel; aheater coupled to an exterior surface of the drying tunnel; nozzlesdisposed between the heater the blower; and a chamber configured tocollect solids; wherein the drying tunnel may be configured to evaporatewater. The blower may be configured to move over 100,000 cubic feet ofair per minute. The drying tunnel may be positioned at angle from about30° to about 90° relative to horizontal.

In other embodiments, a system may comprise a plurality of dryingtunnels, wherein each drying tunnel may comprise a blower, wherein theblower may be fluidly coupled to an end of the drying tunnel; a heatercoupled to an exterior surface of the drying tunnel; nozzles disposedbetween the heater and the blower; a chamber configured to collectsolids; and wherein the drying tunnel is configured to evaporate water.The blower may be configured to move over 100,000 cubic feet of air perminute. The plurality of drying tunnels may be positioned at an anglefrom about 30° to about 90° relative to horizontal.

In some embodiments, a method may comprise supplying water from a bodyof water to a drying tunnel, wherein the drying tunnel may comprise ablower, wherein the blower may be fluidly coupled to an end of thedrying tunnel; a heater coupled to an exterior surface of the dryingtunnel; nozzles disposed between the heater and the blower; a chamberconfigured to collect solids; and wherein the drying tunnel may beconfigured to evaporate the water. The method may further comprisespraying the water into the drying tunnel with the nozzles; capturingand blowing air into the drying tunnel with the blower; heating thewater with the heater; evaporating the water; and collecting solids fromthe water in the chamber. The blower may be configured to move over100,000 cubic feet of air per minute. The drying tunnel may bepositioned at angle from about 30° to about 90° relative to horizontal.

It is believed that the operation and construction of the presentdisclosure will be apparent from the foregoing description. While theapparatus and methods shown or described above have been characterizedas being preferred, various changes and modifications may be madetherein without departing from the spirit and scope of the disclosure asdefined in the following claims.

What is claimed is:
 1. A drying tunnel for evaporating and treatingcontaminated water comprising: a hollow conduit with a proximal end anda distal end spaced apart from the proximal end; a blower fluidlycoupled to the proximal end of the drying tunnel and configured toprovide a stream of air into the drying tunnel; at least one nozzleconfigured to be coupled to a source of contaminated water, the at leastone nozzle disposed between the distal end and the blower and configuredto provide the contaminated water into the drying tunnel and the streamof air passing therethrough; and, a chamber coupled to and disposedexterior to the drying tunnel, the chamber configured to collect solidsfalling out of solution from the contaminated water as the contaminatedwater is evaporated.
 2. The drying tunnel of claim 1, wherein the atleast one nozzle has an ability to adjust a rate of the contaminatedwater entering into the drying tunnel to compensate for the stream ofair temperature to reach full evaporation.
 3. The drying tunnel of claim1, wherein the at least one nozzle is coupled to a pump via a line. 4.The drying tunnel of claim 1, wherein the number of the at least onenozzle is
 32. 5. The drying tunnel of claim 1, wherein the blower isconfigured to move over 100,000 cubic feet of air per minute.
 6. Thedrying tunnel of claim 1, wherein at least one of the blower and thedrying tunnel has an inner diameter from about 8 feet to about 12 feet.7. The drying tunnel of claim 1, wherein a length of the drying tunnelis about 50 feet to about 200 feet.
 8. The drying tunnel of claim 1,wherein the drying tunnel is disposed on a trailer.
 9. The drying tunnelof claim 8, further comprising a lifter coupled between the dryingtunnel and the trailer to adjust an angle of the drying tunnel relativeto horizontal.
 10. The drying tunnel of claim 9, wherein the angle isabout 30° to about 90°.
 11. The drying tunnel of claim 1, wherein thechamber is positioned between the blower and the at least one nozzle.12. A system for evaporating and treating contaminated water comprising:a plurality of drying tunnels, wherein each drying tunnel of theplurality of drying tunnels comprises: a hollow conduit with a proximalend and a distal end spaced apart from the proximal end; a blowerfluidly coupled to the proximal end of the drying tunnel and configuredto provide a stream of air into the drying tunnel; at least one nozzleconfigured to be a coupled to a source of contaminated water, the atleast one nozzle configured to provide the contaminated water into thedrying tunnel and the stream of air passing therethrough; and, a chambercoupled to and disposed exterior to the drying tunnel, the chamberconfigured to collect solids falling out of solution from thecontaminated water as the contaminated water is evaporated.
 13. Thesystem of claim 12, wherein the at least one nozzle has an ability toadjust a rate of the contaminated water entering into the drying tunnelto compensate for the stream of air temperature to reach fullevaporation.
 14. The system of claim 12, wherein the at least one nozzleis coupled to a pump via a line.
 15. The system of claim 12, wherein thenumber of the at least one nozzle is
 32. 16. The system of claim 12,wherein a length of the drying tunnel is about 50 feet to about 200feet.
 17. The system of claim 12, wherein the drying tunnel is disposedon a trailer.
 18. The system of claim 17, further comprising a liftercoupled between the drying tunnel and the trailer to adjust an angle ofthe drying tunnel relative to horizontal.
 19. The system of claim 18,wherein the angle is about 30° to about 90°.
 20. The system of claim 12,wherein the chamber is positioned between the blower and the at leastone nozzle.